Accurate and sensitive multipoint temperature mapping of tumors during hyperthermia treatment, if done in a practical and efficient way, will greatly enhance treatment effectiveness. Temperature during treatment must be maintained between 42 degrees C and 45 degree C, above which the time-temperature threshold for normal tissue tolerance becomes critical. For microwave hyperthermia treatment, a non-metallic temperature probe that is insensitive/immune to direct microwave heating would measure only the tumor tissue temperature. Physical Optics Corporation proposes to develop an optical fiber temperature (OFT) probe that is cost-effective and practical for clinical use. This robust, low-cost probe will accurately and sensitively measure temperature at eight points on the tumor. Its extremely small size (diameter<500 um) will allow it to fit into the catheter that is typically used to administrater microwave hyperthermia treatment in intracavitarial tumors, including benign prostatic hyperplasia. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE